One of well-known conventional techniques is a direction division duplex (DDD) scheme implemented in systems where scattered waves are used directly as carrier waves. In this technique, a circulator is used to carry out equivalent duplexing of a transmitting wave and a received wave based on differences in directiveness between outgoing electromagnetic waves from a base station and incoming electromagnetic waves to the base station. Further details on this technique are found in RFID Handbook 2nd Edition by Klaus Finkenzellar, Translated by Soft Engineering Institute, Industrial Daily Newspaper, May 2004, pp. 45.
In addition, Japanese Patent Application Publication No. 2000-99673 describes how antenna pads are joined to pads of a semiconductor device including an IC chip and an antenna coil.
Japanese Patent Application Publication No. 2006-268090 describes an electrical connecting structure utilizing a tapered or a triangle shape pad for an RFID tag that is provided with an antenna pattern and a circuit chip.
Japanese Patent Application Publication No. 2000-200328 describes arranging a couple of electrodes provided to an IC chip almost at right angles to the length of a base material.
Japanese Patent Application Publication No. 2006-270766 describes preparing a wireless tag having a common dipole antenna length and adjusting the length of the dipole antenna of the wireless tag during its use so that it matches the wavelength of the propagating radio waves.
Lastly, Japanese Patent Application Publication No. 2005-347635 describes a semiconductor device including a semi-conductor chip with both-side electric contact for radio communication and an antenna for transmitting and receiving, in which a conductive bump is formed in a region of an analog circuit including a rectification circuit and a clock circuit, except in regions that may possibly cause electrically undesired coupling to the conductive bump.